Track coupling for electrical distribution tracks

ABSTRACT

A coupler electrically connecting exposed tracks conductors in neighboring lengths of electrical distribution tracks, the coupler having contact elements which are moved by a cam assembly.

PATENTED IAR 5 i974 SHEET 1 UF 3 TRACK COUPLING FOR ELECTRICALDISTRIBUTION TRACKS The present invention relates to a coupler forelectric distribution tracks, and is particularly but not exclusivelysuitable for electrically coupling two lengths'of track of the formdisclosed and claimed in our British Patent Specification No. 1,169,318.

According to the present invention, there is provided a coupler forelectrically connecting conductors in neighbouring lengths of electricaldistribution tracks which are ofthe kind having bare track conductors,the coupler having a casing containing a pair of conductor elementswhich are insulated from one another and a cam assembly operable fromthe exterior of the casing to urge the conductors to positions in which,in use, the conductor elements can clamp the coupler to the neighbouringlengths of track and can each engage one of the track conductors in eachof the two tracks to establish electrical continuity between theconductors engaged thereby.

Preferably` the conductor elements each have two upstanding ears, eachprovided with a contact finger for abutting the end of one trackconductor. The coupler thus has four ears and contact fingers locatedopposite one another forming two opposed pairs of banks of Contactfingers. One pair of opposed fingers is to contact the ends of the trackconductors of one length of track and the other pair is to contact thetrack conductors of the other length of track. In the preferred coupler,two identical cam assemblies are provided to operate the two banks ofcontact fingers independently from one another.

The cam assembly may comprise a cam-shaft, a slidably mounted cam on thecam-shaft, a cam-seat disposed around the cam-shaft, and theconductorelements may be arranged to bias the cam against the cam-seat which isprovided with apair of arcuate inclined surfaces for coactng with thebiased cam to resist movement ofthe cam out of its position in which iturges the conductor-elements apart for abutting the track conductors.With this arrangement, a positive action is needed to move the cam tothe position in which the conductor elements are released from the trackconductors. The cam-seat preferably includes rotational limit stops forthe cam.

The invention will now be described by way of example with reference tothe accompanying drawings, in which:

FIG. 1 is a partial perspective view of two lengths of distributiontrack to be connected by a coupling embodying the present invention;

FIG. 2 is an exploded perspective view illustrating the coupling per se;

FIG. 3 is a longitudinal sectional view through the tracks with thecoupling shown partially in section; and

F 1G. 4 is a cross-sectional view through the coupling and track,takenalong the line lV-IV of FIG. 3.

For clarity, a description of an electric distribution track will firstbe given. Each length of track l consists of an elongate member whichis, for example, an extrusion 11 of a plastics material such as P.V.C.The extrusion has a base l2 and sides 13, 14 extending perpendicularlyfrom the longitudinal edges thereof. The

sides 13, 14 include housings in which track-conductor strips l5, 16 arecarried. The track-conductors l5, 16 are accessible from theinner regionof the extrusion 12 by way of longitudinally-extending recesses or slots17 or 18. A further track-conductor 19 is supported in the base l2 ofthe extrusion 11 and is used to provide an earth line- The sides 13, 14of the extrusion 11 additionally include flanges 22, 23 which arelocated remote from the base 12, and which project inwardly from thesides 13, 14. As viewed in the drawing, the flanges 22, 23 havedownwardly-projecting extensions 24, 25 and a pair of grooves arethereby formed between the extensions 24, 25 and the sides 13, 14. Theflanges 22, 23 and the said grooves 26, 27 extend longitudinally alongthe length of the extrusion 1l. The grooves are provided to accommodatelips 28 of an external covering track 29.

It will be noticed that the extrusion l 1 is of asymmetrical transversecross-section. This asymmetrical shape results from the provision offirstly a longitudinallyextending recess 30 adjacent side 13 andsecondly a surface 31 adjacent the side 14 which is inclined towards thefurther conductor 19.

A track 10 of the above form has been disclosed and claimed in ourBritish Patent No. 1,169,318.

The covering track 29 has a generally T-shaped formation 33 on its upperside 34, as shown in FIG. l, which is used in conjunction withappropriate fixing brackets to secure the track 10 and covering track 29to a wall, ceiling or the like. An elongated T-shaped slot 35 is formedwithin the body of the side 34 and extends inwardly from the ends of thecovering track 29. The slot 35 accommodates a correspondingly T-shapedbar 36 used in fastening adjoining lengths of track l0 to one another.

The adjoining lengths of track 10 are fastened together in the followingmanner. One end of the T- shaped bar 36 is first inserted into onelength of covering track 29 already fitted with the track 10. The bar 36is then secured to the track 10 and covering track, with its other endprojecting therefrom. The bar 36 is secured by a screw 37 which passesthrough the conductor 19, through a hole in the base 12 ofthe extrusion11 and into a screw-threaded aperture in the bar 36. The conductor 19 islocally deformed in the region of the said hole so as to enable the headof screw 37 to be recessed at least partially below the exposed surfaceof the conductor 19. Having secured the bar 36 to one length of track,the second length of track is brought into abutment with the rst and thebar 36 is secured to the second length in the same way. This fasteningensures continuity between the conductors 19 of the separate lengths oftrack 10. When fastening two lengths of track 10 together, it isimportant that their recesses 30 and inclined surfaces 31 are alignedwith each other. This is facilitated using the coupling embodying theinvention, which will shortly be described.

The open ends of the tracks 10 are preferably closed for safety by aplate 40. The plate 40 is a plastics moulding e.g. of P.V.C. lt has twospaced ears 41 which are received within the ends of the recesses orslots 17, 18 that provide access to the track conductors 15, 16. Theplate also has an apertured lug 42 whereby it can be screwed orotherwise secured to the'track 10. The plates 40 may be supplied alreadyfitted to the ends of each length of track 10, and is formed withV-shaped slots 43 enabling the plate to be readily severed therealong.The plates 40 at the adjoining ends of two lengths of track 10 are sosevered to enable a coupling, embodying the invention, to bridge thesaid adjoining ends and their severed plates 40. The severed plates arenot illustrated in the longitudinal sectional view of FIG. 3 for clarityof illustration.

The coupling per se will now be described. The coupling 50 includes acasing 5l which is made from a rigid plastics material such as P.V.C. orglass filled nylon. The casing 51 has a central dividing wall 52 whichseparates the casing into two compartments. A pair of conductor elements53, 54 is provided, one of which is mounted inside each of thecompartments. The conductor elements 53, 54 are therefore kept insulatedfrom one another by the dividing wall 52. The conductor elements aremade from a resilient material such as brass, and as will be seen fromthe drawing, each element includes two spaced, upstanding ears 55. Theears are bent to form contact lingers for engaging the track conductorsl5 or 16 of the separate lengths of track 10 to be coupled. The ears 55incline inwardly towards one another shown, with the distance betweenthe Contact fingers 56 initially less than the distance between thetrack conductors l5, 16. When the coupling 50 is positioned in the twolengths of track 10, the contact fingers 56 are moved apart from theirinnermost positions by deflecting the ears 55 outwardly so that each ispressed into contact with its associated track-conductor. This not onlyestablishes electrical continuity between the conductors and 16,respectively, of the adjoining lengths of track l0 but also clamps thecoupling 50 thereto. When clamped to the tracks 10, the contact fingers56 are engageable with the recesses or slots 17, 18 to prevent thecoupling 50 being inadvertently detached from the tracks l0.

The opposed pairs of ears 5S and their associated contact fingers 56 aremoved outwardly by means of two cam arrangements. The cam arrangementseach operate to press air pair of opposed contact fingers 56 apart. Asthe cam arrangements are identical, only one will be hereinafterdescribed.

The cam arrangement is constituted by a generally elliptical cam 62, acam-seat 63 and a cam-shaft 64. The cam arrangement is assembled withinthe casing follows. The cam shaft 64 is passed through an aperture 65provided in the base of the casing 5l, so that the head 65 ofthecam-shaft 64 is accessible from the exterior of the casing 5l. The head66 of the cam shaft is slotted so that the shaft may be rotated by meansof a screw driver.

The cam-scat 63 is then positioned in the casing 51, on top oftheconductor elements 53, 54. A further aperture 67 is provided in thecam-seat 63 to allow the cam-shaft 64 to extend therethrough. The cam 62is then positioned on the cam shaft 64, upon a square portion thereof soas to rotate with the shaft 64. The cam is retained on the cam-shaft 64by conventional means such as spreading the end ofthe cam-shaft 64.Otherwise, the cam can be retained on the cam-shaft 64, for example byusing a circlip. The cam 62 and its associated cam-seat 63 are both freeto move slightly along the cam-shaft 62 and both are made frominsulating, plastics materials such as polyacetal. A pair of arcuateinclined surfaces 69 are formed on the surface of the cam-seat 63 whichcontacts the cam 62. The inclined surfaces project from the surface 70of the cam-seat 63 to the raised portions 71, which include surfaces71a, 7111, forming rotational limit stops for the cam 62. When thecam-shaft 64 is rotated so as to align the cam 62 with its major axisacross the housing 51, the cam 42 moves the associated pair of ears 55and their contact fingers 40 apart laterally into an on position againstthe resilient bias conferred by the material from which the elements 53,54 are made. The required rotation is anticlockwise as viewed fromabove. The inward inclination of the ears of the resilient conductingelements 59, 54 biases the cam 62 against the cam-seat 63, so that onrotation the cam remains in Contact with and rides on the inclinedsurfaces 49. The cam is held in the "on" position by flats formed on itscamming-surface which engage the ears S5, and further rotation in thesame direction is prevented by the limit stop 71u. lf the cam 62 is nowrotated through approximately 90 in a clockwise direction it is drivenup the inclined surfaces 69 and is correspondingly moved upwardly alongthe cam-shaft 64. The rotation aligns the cam 62 with its major axisparallel to the longitudinal axis of the housing 51, the contact fingersthen having returned to their innermost or off position. Furtherrotation in this direction is prevented by the limit stop 71b. Asdescribed, to allow the Contact fingers 56 to assume their innermost oroff position, it is necessary to rotate the cam 62 in a clockwisedirection and drive it up the inclined surfaces 69. This movement of thecam 62 is resisted however by the co-operation of the resilient,inwardly inclined ears 55 of the conducting elements 53, 54 and theinclined surfaces 69. This resistance ensures that when the contactfingers 56 are in their outermost or on position, inadvertent inwardmovement is prevented, thereby ensuring that the coupler 10 will remainlocked to the two lengths of track 10.

It will be seen that the ends of the casing 51 are similarlyasymmetrical as the tracks 10. Thus, the ends each include an inclinedportion 73 and a lug 73. The coupler 50 will therefore only fit properlyinto the adjoining tracks if their grooves 30 and inclined surfaces 3lare aligned, and if the coupler is offered to the tracks 10 such thatlugs 73 can directly enter the grooves 30. The coupler 50 thereforeserves as a useful check that the two lengths of track 10 are correctlymated whilst fastening them together. The check is preferably carriedout before finally securing the tracks 10 together with the screws 37.When electrical continuity between the track conductors 15, 16 of thecorrected mated lengths of track 10 is established by means of thecoupler 10 and the conductors are connected to a power supply, each ofthe conductors l5 will have one and the same polarity and each of theconductors 16 will have the opposite polarity. Thus, power supplied bythe track 10 to appliances via appropriately asymmetrical connectors(not shown) will be of correct polarity irrespective of whether theconnectors are affixed to one length of track l0 or to the other.

lt will be seen'- that there is a notch 74 centrally formed in oppositesides of the casing 51. The purpose of the notches is to enable thecoupler to bridge adjoining ends of two lengths of track l0 havingsevered end plates 40, as mentioned above, fixed to their ends. Thesevered plates 40 are accommodated in the notches 75 and the arrangementserves to centre the coupler S0 about the junction of the two lengths oftrack l0.

The coupler 50 described and illustrated incorporates two conductorelements 53, 54 providing two spaced pairs of opposed contact fingers56. Each opposed pair of fingers 56 is individual to one of the lengthsof track l0 and the positions of the fingers 56 of each opposed pairthereof is controlled by an associated cam assembly. It will beappreciated that the arrangement could be modified suitably such thatthe elements 53 each need only have one contact finger to establishcontinuity between the'track conductors l5 or 16 of the two lengths oftrack 10. ln this case, only one cam assembly is necessary.

l claim:

l. A coupler for electrically connecting exposed track conductors inneighbouring lengths of electrical distribution tracks, the couplercomprising:

a casing,

a pair of conductive elements, insulated from one another, which arelmounted within said casing for movement between operative andinoperative positions,

and a cam assembly within said casing, but operable from the exteriorthereof, for moving said conductive elements between their operative andinoperative positions,

whereby in their operative positions, said conductive elements, in use,clamp the coupler to the neighbouring lengths of trackA and each engageone of said track conductors in each of said two tracks to establishelectrical continuity between the conductors engaged thereby,

said cam assembly comprising:

a cam-shaft, a slidably mounted cam on said camshaft and a cam-seatdisposed around said camshaft, said cam being biased against saidcam-seat by said conductive elements, and a pair of arcuate inclinedsurfaces being provided on said cam-seat for coaction with said cam toresist movement of said cam from the position thereofn which it urgesthe conductor elements to their operative track conductor-engagingpositions.

2. A coupler according to claim 1, wherein said conductive elements aremounted side by side within said casing and are movable apart uponoperation of'said cam assembly whereby said conductive elements, in use,press against spaced-apart track conductors located on opposite sides ofthe tracks.

3. A coupler according to claim 2, wherein each conductive clement hasan outwardly-directed contact iinger for engaging the appropriate trackconductors.

4. A coupler according to claim 3, wherein each conductive element has apair of spaced, upstanding ears each carrying an outwardly-directedContact finger, individual cam assemblies being provided to control thepositions of said lingers of each opposed pair of ears.

5. A coupler according to claim l, wherein said camseat includesrotational limit stops for said cam.

6. Electric distribution apparatus including at least two lengths ofdistribution track joined together electrically by a coupler as claimedin claim l.

7. A coupler for electrically connecting exposed track conductors inneighbouring lengths of electric distribution tracks, the couplercomprising:

a casing,

a pair of conductive elements, insulated from one another, which aremounted within said casing, each of said elements having two spaced,upstanding ears and each ear carrying an outwardly-directed Y contactfinger,

said elements being mounted sidebyside with their ears located oppositeone another, said ears being movable apart whereby in use, said contactlingers press against the track conductors on opposite sides of thetracks to clamp said coupler to said tracks, each element engaging oneof said track conductors in each of said two tracks to establishelectrical continuity between the conductors engaged thereby, i

and two cam assemblies within said casing, each of which is operablefrom the exterior thereof to effect movement of one of the oppositepairs of said ears,

said cam assemblies each comprising a cam, a camshaft and a cam seatmounted for movement along said camshaft, said cam seat being biasedagainst said cam by said conductive elements, and said cam seat having apair of arcuately-inclined surfaces for coaction with said cam to resistmovement of said cam from the position thereof in which it urges saidconductive elements to their track conductor-engaging position.

8. A coupler according to claim 7, wherein said conductive elements aremovable against a biasing force when each cam assembly is operated tourge their contact fingers into engagement with said track conductors.

9. A coupler according to claim 7, wherein said camseat includesrotational limit stops for said cam.

10. A coupler according to claim 7, wherein said cam is generallyelliptical and has flats formed at its opposite ends to coact with saidconductive elements to aid in resisting movement of said conductiveelements from their track conductor-engaging positions.

* l l l

1. A coupler for electrically connecting exposed track conductors in neighbouring lengths of electrical distribution tracks, the coupler comprising: a casing, a pair of conductive elements, insulated from one another, which are mounted within said casing for movement between operative and inoperative positions, and a cam assembly within said casing, but operable from the exterior thereof, for moving said conductive elements between their operative and inoperative positions, whereby in their operative positions, said conductive elements, in use, clamp the coupler to the neighbouring lengths of track and each engage one of said track conductors in each of said two tracks to establish electrical continuity between the conductors engaged thereby, said Cam assembly comprising: a cam-shaft, a slidably mounted cam on said cam-shaft and a camseat disposed around said cam-shaft, said cam being biased against said cam-seat by said conductive elements, and a pair of arcuate inclined surfaces being provided on said cam-seat for coaction with said cam to resist movement of said cam from the position thereof in which it urges the conductor elements to their operative track conductor-engaging positions.
 2. A coupler according to claim 1, wherein said conductive elements are mounted side by side within said casing and are movable apart upon operation of said cam assembly whereby said conductive elements, in use, press against spaced-apart track conductors located on opposite sides of the tracks.
 3. A coupler according to claim 2, wherein each conductive element has an outwardly-directed contact finger for engaging the appropriate track conductors.
 4. A coupler according to claim 3, wherein each conductive element has a pair of spaced, upstanding ears each carrying an outwardly-directed contact finger, individual cam assemblies being provided to control the positions of said fingers of each opposed pair of ears.
 5. A coupler according to claim 1, wherein said cam-seat includes rotational limit stops for said cam.
 6. Electric distribution apparatus including at least two lengths of distribution track joined together electrically by a coupler as claimed in claim
 1. 7. A coupler for electrically connecting exposed track conductors in neighbouring lengths of electric distribution tracks, the coupler comprising: a casing, a pair of conductive elements, insulated from one another, which are mounted within said casing, each of said elements having two spaced, upstanding ears and each ear carrying an outwardly-directed contact finger, said elements being mounted side-by-side with their ears located opposite one another, said ears being movable apart whereby in use, said contact fingers press against the track conductors on opposite sides of the tracks to clamp said coupler to said tracks, each element engaging one of said track conductors in each of said two tracks to establish electrical continuity between the conductors engaged thereby, and two cam assemblies within said casing, each of which is operable from the exterior thereof to effect movement of one of the opposite pairs of said ears, said cam assemblies each comprising a cam, a camshaft and a cam seat mounted for movement along said camshaft, said cam seat being biased against said cam by said conductive elements, and said cam seat having a pair of arcuately-inclined surfaces for coaction with said cam to resist movement of said cam from the position thereof in which it urges said conductive elements to their track conductor-engaging position.
 8. A coupler according to claim 7, wherein said conductive elements are movable against a biasing force when each cam assembly is operated to urge their contact fingers into engagement with said track conductors.
 9. A coupler according to claim 7, wherein said cam-seat includes rotational limit stops for said cam.
 10. A coupler according to claim 7, wherein said cam is generally elliptical and has flats formed at its opposite ends to coact with said conductive elements to aid in resisting movement of said conductive elements from their track conductor-engaging positions. 